1. Field
One embodiment of the invention relates to a sound quality control apparatus, a sound quality control method, and a sound quality control program for adaptively performing sound quality control processing on each of a speech signal and a music signal contained in an audio (audible frequency) signal to be reproduced.
2. Description of the Related Art
As is well known, for example, a broadcasting receiving apparatus for receiving TV broadcasting and an information reproducing apparatus for reproducing recorded information from an information recording medium perform sound quality control processing on an audio signal to further improve sound quality when the audio signal is reproduced from a received broadcast signal or a signal read from the information recording medium.
In this case, content of the sound quality control processing performed on an audio signal depends on whether the audio signal is a speech signal such as a talking voice of a person or a music (non-voice) signal such as a musical piece. That is, for a speech signal, sound quality is improved by performing sound quality control processing so as to emphasize center-localized components for articulation like talk scenes and sport live broadcasting and, for a music signal, sound quality is improved by performing sound quality control processing with a sense of spread and an emphasized sense of stereo.
Thus, determining whether a received audio signal is a speech signal or a music signal and then performing corresponding sound quality control processing in accordance with a determination result thereof can be considered. However, a speech signal and a music signal are frequently mixed in an actual audio signal and thus, determination processing is often difficult and so, it cannot be currently said that suitable sound quality control processing is performed on an audio signal.
Jpn. Pat. Appln. KOKAI Publication No. 7-13586 discloses a configuration in which an acoustic signal is classified into three types of “speech”, “non-speech”, and “undefined” by analyzing the zero-crossing count, power fluctuations and the like of the input acoustic signal, and frequency characteristics with respect to the acoustic signal are controlled to emphasize the voice frequency band when the acoustic signal is determined as “speech”, frequency characteristics are controlled to be flat when determined as “non-speech”, and frequency characteristics are controlled to maintain characteristics of the previous determination when determined as “undefined”.